SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b1b1f69694c324a4ecc16c570a446164a60658b05f4a24cae39024b103a3506' 
  AND token = 'QuAiQVLIUwaZHHsmcPy6ZoZe3ec/OGiUAKU9LcskDKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}